JPH0823315B2 - Control device for engine with supercharger - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a control device for an engine with a supercharger, and more particularly to changing the intake / exhaust overlap period and supercharging the engine with a mechanical supercharger. Regarding what you did.

(Prior Art) Conventionally, as a control device for an engine with a supercharger, as disclosed in, for example, Japanese Patent Laid-Open No. 61-197720, a mechanical supercharger is provided in an intake passage, and the supercharger is a clutch. Is connected to the engine output shaft via, and in the supercharging region on the high load side, the clutch is connected to supercharge the engine and increase its output.
In the areas other than the supercharging region, the clutch is disengaged and the engine is operated by natural intake to reduce fuel consumption. In addition, the engine valve system is equipped with a timing changer that is driven by a step motor and that changes the intake / exhaust timing, so that the intake / exhaust overlap period is made larger in the supercharging region than in the non-supercharging region. There is also known a technique in which the occurrence of knocking is suppressed by reducing the effective stroke of (1) to substantially reduce the compression ratio.

(Problems to be Solved by the Invention) In the engine with a supercharger, when the intake / exhaust overlap period is increased in the supercharging region, intake air whose pressure is higher than that of the exhaust gas on the exhaust passage side (that is, Supply pressure)
Since the residual gas in the cylinder is sufficiently scavenged and the inside of the cylinder is sufficiently cooled, the occurrence of knocking at the time of supercharging can be effectively prevented.

However, in this case, if the operating range in which the intake / exhaust overlap period is increased and the operating range of the turbocharger are simply made to coincide with each other, there is a delay in the variable operation of the intake / exhaust timing by the timing changing device. Therefore, there is a problem in that the occurrence of knocking cannot be sufficiently prevented due to the variable delay of the intake / exhaust timing at the start of supercharging.

The present invention has been made in view of the above point, and an object thereof is to consider the timing change device early before supercharging start in consideration of the variable delay of the intake / exhaust timing by the timing change device. By performing variable control and increasing the intake / exhaust overlap period before entering the supercharging region, knocking that occurs due to the variable delay of the above timing changing device at the start of supercharging is prevented and supercharging is performed. The purpose of this is to effectively prevent the occurrence of knocking.

(Means for Solving the Problem) In order to achieve the above object, in the present invention, the operation region in which the intake / exhaust overlap period is increased by the timing changing device is set to a non-supercharging region in which the mechanical supercharger is not operated. It is to enlarge up to.

Specifically, the solution means taken by the present invention includes a timing changing device for varying intake timing or exhaust timing, and a mechanical supercharger connected to an engine output shaft through a clutch to supercharge intake air. In order to increase the intake / exhaust overlap period in this supercharging region, the clutch is engaged to operate the mechanical supercharger in the supercharging region where the engine load is higher than the set value. In a control device for an engine with a supercharger configured to control the timing changing device, the timing changing is performed so that the intake / exhaust overlap period becomes large before reaching a supercharging start region in which the clutch is connected. A configuration in which the control range for increasing the intake / exhaust overlap period of the device is expanded to the non-supercharging region where the clutch is separated A.

(Operation) According to the present invention, in the present invention, the clutch is connected in the high load side supercharging region to supercharge the engine and the output thereof is increased, while the clutch is disengaged outside the supercharging region. Is driven by natural aspiration, which reduces fuel consumption.

Further, the operation of the timing changing device increases the intake / exhaust overlap period in the supercharging region on the high load side of the engine, thereby promoting the scavenging of the residual gas in the cylinder.

Since the control range of the timing change device that increases the intake / exhaust overlap period is set to be expanded to the non-supercharging region where the clutch is separated, the engine can be operated from the low load region to the high load region such as during acceleration. When moving to
First, the engine enters the large overlap region, and the intake / exhaust overlap period increases due to the operation of the timing changing device, then enters the supercharging region, the clutch is engaged, and the engine is supercharged. That is, because the turbocharger operates and the engine is supercharged with the intake / exhaust overlap period increased by compensating for the variable delay of the timing changing device, the pressure becomes higher than the exhaust gas on the exhaust passage side. Since the residual gas in the cylinder is sufficiently scavenged by the intake air (supercharging pressure) and the inside of the cylinder can be sufficiently cooled, knocking caused by the variable delay of the timing changing device at the start of supercharging is prevented. It is possible to effectively prevent the occurrence of knocking at the time of supercharging.

(Example) Hereinafter, the Example of this invention is described based on drawing.

FIG. 1 is a DOHC equipped with a control device according to an embodiment of the present invention.
1 shows a type of supercharged engine. In the figure, reference numeral 1 is an engine, 2 is a cylinder formed in the engine, and a piston 3 is slidably fitted in the cylinder 2, and a combustion chamber 4 is formed by the cylinder 2 and the piston 3. Are formed. The piston 3 is connected to a crankshaft 6 via a connecting rod 5. Also, 7
Has one end connected to the combustion chamber 4 and the other end connected to the air cleaner 8
The intake passage 9 is open to the atmosphere via the, and an exhaust passage 9 is connected to the combustion chamber 4 at one end and is open to the atmosphere at the other end.

At the opening of the intake passage 7 to the combustion chamber 4, an intake valve 11
However, at the opening of the exhaust passage 9 to the combustion chamber 4, the exhaust valve 12
Are arranged respectively. The intake valve 11 and the exhaust valve 12
Are driven by the intake cam shaft 13 and the exhaust cam shaft 14 at predetermined timings.

Further, in the intake passage 7, a throttle valve 16 for adjusting the intake flow rate, a mechanical supercharger 17 for pressurizing the intake air, a surge tank 18, and fuel for the intake air are sequentially provided from the upstream side of the intake air. An injector 19 for injection and supply is provided. Further, the intake passage 7 is provided with a bypass passage 21 that bypasses the supercharger 17, and the bypass passage 21 is provided with a control valve 22 that opens the control valve 22 when the supercharger 17 is stopped. The intake air is supplied to the combustion chamber 4 via the bypass passage 21.

Further, the exhaust camshaft 14 is provided with a timing changing device 30 for varying the exhaust timing. That is, as shown in FIG. 1, the exhaust camshaft 14 is divided into a drive gear portion 31 that receives a driving force from the crankshaft 6 and a driven portion 32 other than the drive gear portion 31. And the drive gear portion
Helical gears are respectively formed on the portions of the driven portion 31 and the driven portion 32 which face each other, and a sleeve 33 provided so as to be meshed with both of these helical gears by a hydraulic actuator 34 in the camshaft direction. By moving the driving gear portion 31 to the driven portion 32, the rotation phase between the driving gear portion 31 and the driven portion 32 is adjusted to make the exhaust timing variable (see FIG. 2).

Further, 51 is provided in the intake passage 7, an air flow meter for detecting the intake air flow rate, 52 is provided in the engine 1 and a rotation speed sensor for detecting the engine rotation speed, 53
Is a load sensor for detecting the load of the engine based on the opening of the throttle valve 16. The output signals of these sensors 51 to 53 are input to the control unit 50, respectively.

The timing changing device 30 is a control unit 50.
Controlled by. That is, as shown in FIG.
In the large overlap area on the high speed / high load side of the “diagonal line”, the exhaust timing is shifted to the crank angle delay side to increase the intake / exhaust overlap period, as shown by the solid line in FIG. In the region on the low speed and low load side of the "diagonal line", the exhaust timing is shifted to the crank angle advancing side to reduce the intake / exhaust overlap period, as shown by the broken line in FIG. Here, the load parameter of FIG. 3 is obtained as the throttle valve opening rate,
It may be replaced with an intake charge amount obtained by dividing the intake air amount by the engine speed. The timing changing device 30 may be an electric type other than the hydraulic type, for example, an electric type including a step motor. Further, a timing changing device may be provided on the intake camshaft 1.

Further, a driven pulley 41 is attached to the drive shaft 17a of the mechanical supercharger 17, and a crank pulley 42 is attached to the crankshaft 6, respectively.
A belt 43 is wound around 42, and the mechanical supercharger 17 is driven by the crankshaft 6. An electromagnetic clutch 44 is provided on the drive shaft 17a of the mechanical supercharger 17, and the mechanical supercharger 17 is operated or stopped by connecting or disconnecting the electromagnetic clutch 44.

The electromagnetic clutch 44 is controlled by the control unit 50. That is, as shown in FIG. 3, the electromagnetic clutch 44 is provided in the supercharging region on the high-speed and high-load side of the "polygonal line".
Is connected to operate the mechanical supercharger 17, while the electromagnetic clutch is operated in the area on the low speed and low load side of the "polygonal line" in FIG.
44 is separated and the mechanical supercharger 17 is stopped.

The control of the timing changing device 30 and the electromagnetic clutch 44 is shown in the block diagram of FIG. Here, 61 is a load comparison circuit, which compares the output signal of the load sensor 53 with a set value. Reference numeral 62 denotes an engine speed comparison circuit, which compares the output signal of the speed sensor 52 with a set value. The output signal of the load comparison circuit 61 and the output signal of the engine speed comparison circuit 62 are input to the OR circuit 65, and the output signal of the OR circuit 65 is input to the electromagnetic clutch 44.

Further, 63 is an overlap period change area setting circuit, which receives the output signal of the rotation speed sensor 52 and outputs a switching load amount corresponding to the engine rotation speed. further,
Reference numeral 64 denotes a load comparison circuit, which compares the output signal of the load sensor 53 with the output signal of the overlap period change area setting circuit 63. The output signal of the load comparison circuit 64 is input to the drive gear unit 31 of the timing changing device 30.

Then, as shown in FIG. 3, the large overlap area is set to be larger than the supercharging area on the low load side, that is, to the non-supercharging area.

Next, the operation of the above-described embodiment will be described. In the supercharging region on the high load side, the electromagnetic clutch 44 is connected to supercharge the engine 1 to increase its output, while the electromagnetic clutch is outside the supercharging region. 4 is separated, the engine 1 is operated by natural intake, and fuel consumption is reduced.

Further, the operation of the timing changing device 30 increases the intake / exhaust overlap period in the supercharging region on the high load side, and promotes the scavenging of the residual gas in the cylinder 2.

Since the control range of the timing changing device 30 for increasing the intake / exhaust overlap period is expanded to the non-supercharging region, the engine 1 shifts from the low load region to the high load region such as during acceleration. In this case, as shown in FIG. 4, as the throttle opening increases, the engine 1 first enters the large overlap region and the timing change device 30 operates to increase the intake / exhaust overlap period, and then the supercharge. Entering the area, the electromagnetic clutch 44 is connected and the engine 1 is supercharged. That is, the supercharger 17 is operated and the engine 1 is supercharged in a state where the operation change of the timing changing device 30 is compensated and the intake / exhaust overlap period is substantially increased. Therefore, the period during which supercharging is performed without completely increasing the intake / exhaust overlap period at the start of supercharging (the period shown as "knock countermeasure required time" in FIG. 4) becomes short. Therefore, the residual gas in the cylinder 2 is sufficiently scavenged by the intake air (supercharging pressure) whose pressure is higher than that of the exhaust gas on the exhaust passage side, and the inside of the cylinder 2 is sufficiently cooled. It is possible to prevent knocking that occurs due to the operation delay of the timing changing device 30 and effectively prevent knocking during supercharging.

In that case, in order to prevent the occurrence of knocking in this "knock countermeasure required time", for example, a knock countermeasure such as correcting the ignition timing may be taken, but even in that case, the "knock countermeasure required time" is short. Also, there are few knock measures.

(Effects of the Invention) As described above, according to the control device for a supercharged engine of the present invention, a timing changing device that makes intake timing or exhaust timing variable and a engine output shaft connected via a clutch. Mechanical supercharger, the clutch is connected in the supercharging region, and the timing changing device is controlled so that the intake / exhaust overlap period becomes large in the supercharging region. Since the control range of the above timing changing device for increasing the lap period is expanded to the non-supercharging region, the clutch output is improved by connecting / disconnecting the clutch and the fuel consumption is reduced. With the basic effect of promoting scavenging of residual gas,
It is possible to prevent the occurrence of knocking due to the variable delay of the timing changing device at the start of supercharging, and to effectively prevent the occurrence of knocking during supercharging such as acceleration.

[Brief description of drawings]

The drawings illustrate an embodiment of the present invention, FIG. 1 is an overall schematic configuration diagram, FIG. 2 is an explanatory diagram showing the operation of a timing changing device,
FIG. 3 is an explanatory diagram showing a supercharging region and a large overlap region, FIG. 4 is an explanatory diagram showing changes in intake / exhaust overlap period, supercharging pressure and throttle opening, and FIG. 5 is a timing changing device and It is a block diagram explaining control of an electromagnetic clutch. 17 …… Mechanical supercharger, 30 …… Timing changer, 44…
… Electromagnetic clutch.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number in the agency FI Technical indication location F02D 43/00 301 R Z (72) Inventor Junzo Sasaki 3-3 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda shares In-company (72) Inventor Hidefumi Fujimoto 3-3 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. (56) References JP 61-187543 (JP, A) JP 59-90718 (JP, A) ) JP-A-61-197720 (JP, A) JP-A-62-170725 (JP, A) JP-A-61-190120 (JP, A) Actually developed JP-A-59-160824 (JP, U)

Claims (1)

[Claims] 1. A timing changing device for changing intake timing or exhaust timing, and a mechanical supercharger connected to an engine output shaft through a clutch for supercharging intake air, wherein an engine load is equal to or more than a set value. In the supercharging region which is the high load region of the above, the clutch is connected to operate the mechanical supercharger, and in the supercharging region, the timing changing device is controlled so that the intake / exhaust overlap period becomes large. In the control device for an engine with a supercharger, the intake / exhaust overlap of the timing changing device is set so that the intake / exhaust overlap period becomes large before reaching the supercharge start region where the clutch is connected. Control of a supercharged engine characterized in that the control range for increasing the period is expanded to the non-supercharging region where the clutch is separated apparatus.